Closes https://github.com/cython/cython/issues/1355

Closes https://github.com/cython/cython/issues/3242

I think this approach is more satisfactory than the old way it used to "work", where "fused_to_specific" was permanently added to the module scope containing the fused type (in this case the Cython scope), was applied in "Scope.lookup_type", but continued to have an effect on the scope forever.

Closes https://github.com/cython/cython/issues/3881

Detect _MSC_VER for __PYX_STD_MOVE_IF_SUPPORTED to support MSVC support even when "__cplusplus" is not set appropriately (GH-3792)

Simplify the output stream capturing for the C compiler runs by using a temp file instead of threads.

Disable the embedding test on MacOS-X to get the builds green again. Too many PRs depend on the travis tests to give a green light.

Improve error reporting when users mistakenly write "&&" or "||" instead of Python's "and" and "or" operators. (GH-3858)

Closes https://github.com/cython/cython/issues/3830

It seems to be unused and it looked like the existing implementation was faulty.

Make type identifier escaping deterministic: hash() hashing lead to unpredictable random prefixes for long names across multiple Python runs.

Split a combined assert in two to avoid an unused C temp variable when assertions are disabled. (GH-3870)

Split a combined assert in two to avoid an unused C temp variable when assertions are disabled. (GH-3870)

`xml.etree.ElementTree.Element.getiterator()` was deprecated in Python
2.7 & 3.2 and removed in Python 3.9.

`xml.etree.ElementTree.Element.getiterator()` was deprecated in Python
2.7 & 3.2 and removed in the freshly released Python 3.9.

"synchapi.h" is not supposed to be included directly, and "windows.h" can break ... other stuff.
Let's see what we can do.

Looks like the usual macro on Windows is "_WIN32" and not "WIN32". Let's support both, to be on the safe side.

Move a memoryview test out of the "run" test directory since memoryview tests tend to be slow and have their own test directory.

- hash() hashing lead to unpredictable random prefixes for long names across multiple runs
- use a single regex run instead of repeated calls to replace()

Fixes https://github.com/cython/cython/issues/3843